Hoyeraal-Hreidarsson Syndrome (HHS)

Dyskeratosis congenita (DC) is a bone-marrow failure syndrome characterized by early onset of reticulate skin hyperpigmentation, nail dystrophy, hyperkeratotic palms, hypotrichosis, atresia of the lacrimal ducts, poor dentition, and oral leukoplakia. The progressive bone-marrow failure affects the majority of cases. There is heterogeneity in the severity of the bone-marrow failure as well as in the range of associated anomalies, and an increased risk for a variety of malignancies. Some patients may be initially characterized as having constitutional or idiopathic aplastic anemia or myelodysplastic syndromes. Hoyeraal-Hreidarsson Syndrome is a severe form of X-linked DC with microcephaly, growth and mental retardation, spastic paresis, ataxia and immunodeficiency. In all forms, telomere protection or maintenance is defective.

Tests Available

Forms and Documents

Test Details

  • 1. Confirmation of a clinical diagnosis.
  • 2. Carrier testing for family members of the affected patient
  • 3. Confirmation that a potential hematopoietic stem cell transplant donor is not affected
  • 4. Prenatal diagnosis in at-risk pregnancies


3 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs

*Reporting times are typical, but could be extended in situations outside GeneDx's reasonable control.


  • 284 Aplastic anemia and other bone marrow failure syndromes
For price inquiries please email zebras@genedx.com

**The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.


  1. Vulliamy TJ, et al, Mutations in dyskeratosis congenita, Blood 107:2680-2685, 2006
  2. Vulliamy TJ, et al, The RNA component of telomerase is mutated in autosomal dominant dyskeratosis congenital, 2001, Nature 413:432
  3. He J, et al, Targeted disruption of Dkc1, the gene mutated in X-linked dyskeratosis congenital causes embryonic lethality in mice. 2002, Oncogene 21:7740